New Hampshire Cosmetology Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

PPD, or para-phenylenediamine, is commonly used in hair dyes, particularly in darker shades, as a primary coloring agent. It is known to be a sensitizing agent, which means that it can cause allergic reactions in some individuals. The allergic reactions can manifest as symptoms like itching, redness, swelling, and in severe cases, anaphylactic reactions. This is significant for cosmetologists to be aware of, as they often conduct patch tests to check for sensitivity before applying hair dye to a client's hair.

While ammonia is present in many hair dyes to help open the hair cuticle for better color penetration, it typically does not cause allergic reactions in the same way that PPD does. Hydrogen peroxide, an oxidizing agent used in hair coloring for developing the dye, is also not primarily associated with allergies but can cause irritation due to its strong oxidizing properties. Alcohol is sometimes used in hair products for its solvent properties, but it is less frequently linked to allergic reactions compared to PPD.

In summary, PPD's reputation as a common allergen in hair dyes underlines the importance of client safety and the need for cosmetologists to be vigilant about potential allergic reactions when using products containing this chemical.